Miniaturised medium pressure capillary liquid chromatography system with flexible open platform design using...

Area of Science:

• Analytical Chemistry
• Microfluidics
• Instrumentation

Background:

• Portable analytical instrumentation is increasingly important for on-site measurements.
• Developments in portable liquid chromatography (LC) have lagged behind other analytical techniques.
• There is a need for accessible, miniaturized LC systems capable of rapid, on-site analysis.

Purpose of the Study:

• To design and develop a miniaturized medium pressure capillary LC (MPLC) system with gradient elution capability.
• To utilize a flexible, modular microfluidic system with low-cost, off-the-shelf components for wide accessibility.
• To evaluate the performance of the developed portable LC system for on-site measurements.

Main Methods:

• Assembled a microfluidic platform on a breadboard using microsyringe pumps and switch valves.
• Incorporated an injection valve and on-capillary detectors, controlled via PC.
• Utilized four miniaturized microsyringe pumps for gradient elution, a nano-LC sampling valve for injection, and a monolithic capillary column with on-capillary UV-vis detection.

Main Results:

• The 5 μL microsyringe pump provided optimal performance, reaching pressures up to 11.4 MPa.
• Gradient pumping repeatability ranged from 4-9% for specified gradient rates.
• Analyte analysis (dyes, pharmaceuticals) showed good repeatability, with relative standard deviations (RSD) of 0.7-1.4% (isocratic) and 1.2-4.6% (gradient) for retention time.

Conclusions:

• A functional portable LC system with gradient elution capability was successfully developed.
• The system's modular design and use of accessible components facilitate wider adoption by analysts.
• The demonstrated performance indicates suitability for rapid, on-site analytical applications.